It's not what your observed max voltage is, it's what voltage the car spends most of its time at.
The voltage is supposed to vary with the temperature sensed at the alternator (a proxy for the temperature at the battery), so I suggest observing how much of your driving is at what voltage. It always starts high, and then drops down as the engine compartment heats up. If you are putting in many minutes or hours at too low a voltage---It seems that what constitutes "too low" is not an exact science---boost the voltage. Try not to let it go above 14.9-15V for any substantial length of time. The fixed 0.6V boost unit would have worked for my 4Runner, but I didn't know that when I began the voltage adventure, so I figured I'd get the adjustable one. When I first decided to get one, the adjustable units were out of stock. Within a few weeks/months, they became available again. I consider the concept of doing this an experiment, although supposedly thousands of satisfied Aussies use these things on their utes and Land Cruisers.
YMMV-
Results not guaranteed-
Good luck with your "experiment"!

Understood. i drove about 300 miles yesterday and around 14.10 was what I saw most of the time. Wondering if throwing the battery on my NOCO genius charger every now and again is good enough to keep the battery happy.

Everything I've seen seems to show the ideal charge voltage for an AGM to be 0.1-0.4V higher than FLA. Toyota/Denso is generally pretty conservative with charging voltages (on the low side, I mean - compare to most US manufacturers), but things have been working just fine for the last 25 years for 3rd gens... why change it? The OEM charge voltage may not be as efficient at charging an AGM, but the float voltage will still be correct for battery health.

That said, an overnight on a trickle charger ever 1-3 months is a good idea. That's what I do on our vehicles, generally.
4Runner: 105A upgraded Denso, sits a week or two regularly but driven long drives when driven
Van: 150A factory alternator, but lots of short trips
Volt: 130A factory DC-DC converter, factory AGM 12V battery
Camry: Tiny Miata battery (U1R), always on the trickle unless being driven

-Charlie

Update. I went ahead and ordered the fixed voltage booster. Due to the current exchange rate ( 1 AUD = 0.65 USD) it comes out to 49 USD landed (free shipping basically). I'm spending free money on this probably unneeded fuse, so don't @ me.

Subtotal: $50.00
Shipping: $22.00
Grand Total: $72.00 AUD

I'll post some before/after shots of the V readings if I see a change.

This is with the GM AC Clutch diode. If put in backwards the battery light comes on. I’m going to add the 7.5a fuse to it also.


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If anyone wants to try one, let me know above.